[EMS Discuss] HIgher current H-Bridge and circuit help

Sat Apr 6 11:35:54 PDT 2013

That sounds almost perfect, but from the description on the DPPT relay link
you posted the motor will always rotate with one of those, the circuit I
built stops it based on input from switches and it needs to be stopped most
of the time...I can cut power to the vcc of the DPDT relay to stop it from
turning I guess...

On Sat, Apr 6, 2013 at 11:12 AM, Taper Wickel <EMAIL HIDDEN> wrote:

> My quick reaction is to go with relays -- and on consideration, that
> original switch is probably just a DPDT wired with each "throw" inverted.
> Er, reading that back, maybe this page will make things clearer:
> http://www.engineersgarage.com/electronic-components/dpdt-double-pole-double-throw-relay
> What you lose, compared to an H-bridge, is the capacity for speed control,
> but in this application it doesn't sound vital.
> Hope this helps!
> Taper.
> --
> Taper Wickel <EMAIL HIDDEN>
> Hi all!
> I hope someone may be able to help me to decide what direction to take a
> project that semi-works but doesn't complete the goal set out.
> I have a chicken door opening mechanism built using an electronic
> screwdriver powered from 4 AA batteries, it has a spool on the driver area
> and it winds up a rope that pulls up the door through a pulley system. The
> switch on the screwdriver is a weird type that throws both negative and
> positive at once and then reverses that for the other direction, thereby
> avoiding the need for any IC or control. The way we operate it is to hold
> the button while the door goes up or down and release it when it is in the
> correct spot. This all works fine and has been in place for a while.
> However now that it gets light earlier I have built a circuit that will
> automatically open the door when it gets light. It uses an H-Bridge to
> control the motor instead of the direct connection to the batteries as
> before, which worked great in testing with a motor with no load on it,
> however once I built it all and tried to put it in place the current of the
> H-Bridge(600ma) was not enough to open the door at more than a snails pace.
> My question is: should I continue to look for another higher amperage (to
> let all the juice from the batteries through would be a much higher
> amperage, like 1 amp)H-Bridge with a similar pinout layout or try to use
> relays to switch it, or try to use some transistors to do it?
> Thanks for any help!
> Cord
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